National Sleep Foundation

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Chapter 1: Normal Sleep

The Physiology of Sleep  The Cardiovascular System

Blood pressure and heart rates both change during sleep. There are brief increases in the person’s blood pressure and heart rate during K-complexes, sleep arousals, and large body movements. In the few hours before a person wakes up, and as the person wakes up in the morning, there is an increase in both heart rate and blood pressure (this may contribute to the higher risk of having a heart attack in the early morning and soon after awakening)67.

Lack of sleep and disordered sleep are also associated with heart attacks and, possibly, stroke. Arrhythmias occur very commonly during sleep and are influenced by the circadian rhythm. They may be significantly increased in those with obstructive sleep apnea and other sleep disorders. These may lead to cardiac events including sudden death.68 69 Just one night of acute sleep loss (3.6 hours of sleep) resulted in increased blood pressure in otherwise healthy young men. One large study found that getting 5 or fewer hours of sleep per night was associated with a 45 percent increase in the risk of heart attack (the researchers controlled for age, weight, smoking, and snoring). Interestingly, higher risk was also found among those who slept for 9 or more hours per night.7